This invention relates to oxygen fuel burners of the type that can be used with industrial furnaces for high temperature heating of work products, where the fuel and oxygen are mixed together to form a high velocity flame that is directed toward the work product in the furnace. More particularly, the invention relates to an oxygen fuel burner that utilizes the fuel both for cooling the combustion chamber and for forming a flame in the combustion chamber. A stream of high velocity oxygen moves along the longitudinal axis of the combustion chamber and the fuel is added to the periphery of the oxygen stream to form a cylindrical flame in the combustion chamber. Additional fuel is added in a circular pattern about the flame outside the combustion chamber. If more oxygen is used than is necessary to support complete combustion of the fuel, the fuel heats the excess oxygen as the flame moves toward the work product and the excess oxygen functions to oxygen-lance the work product.
High velocity burners are utilized in industrial furnaces, either alone or in combination with electrodes in electric arc furnaces for rapidly and efficiently melting a work product such as steel. It is desirable to direct the flame from a burner toward the work product so that the heat from the flame is transferred directly to the work product. In addition, it is desirable to direct a stream of oxygen toward a work product in a furnace so as to oxygen-lance the work product.
In the past, oxygen lancing has been accomplished by opening the door of the furnace, projecting a metal tube into the furnace and then moving a stream of oxygen through the tube to move the oxygen into intimate contact with the hot work product. The tube was manipulated so as to direct the stream of oxygen emerging from the tube toward the work product. Of course, a substantial amount of heat is lost when the door of the furnace remains open during the oxygen lancing procedure, the end of the tube projected into the furnace tends to deteriorate, and a substantial amount of the oxygen is lost in the atmosphere of the furnace because the oxygen is not very hot when it emerges from the oxygen lancing tube and engages the work product.
Recently, as described in U.S. Pat. No. 4,473,350, heating a work product in an industrial furnace with a high velocity flame has been accomplished by moving a stream of oxygen through a burner and adding fuel in a circular arrangement about the stream of oxygen so that the fuel tends to film-cool the surface of the combustion chamber. Later is was determined that oxygen lancing of the work product could be accomplished with the burner of the type disclosed in U.S. Pat. No. 4,473,350 by supplying excess oxygen through the combustion chamber of the burner. The flame carries the excess oxygen on out into the furnace, the flame heats the oxygen, and when the unburned oxygen engages the work product the oxygen will have been preheated by the flame and readily reacts with the metal product. These new oxygen fuel burners avoid the requirement of opening a furnace door and inserting the conventional lancing tube through the door. However, the radiation of heat from the work product and the flame within the furnace, and the convection heat transmitted from the flame and elements within the furnace to the face of the burner tend to rapidly deteriorate the burner. Moreover, the prior art high velocity oxygen fuel burners have included, in some cases, a graphite burner block that resists rapid deterioration from exposure to heat. While the graphite burner block resists deterioration from heat, it has been found that the porous nature of graphite permits some of the fuel to seep through the burner block to the outside of the furnace, causing minor fires in the vicinity of the burner block. The exterior flame is hazardous to the workers about the furnace, tends to deteriorate the conduits, fittings and other elements in the vicinity of the burners, and wastes energy.